The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a ...
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The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a pendulum clock's accuracy resides in its pendulum. If the pendulum is accurate, the clock will be accurate. This book describes many scientific aspects of pendulum design and operation in simple terms with experimental data, and little mathematics. It has been written, looking at all the different parts and aspects of the pendulum in great detail, chapter by chapter, reflecting the degree of attention necessary for making a pendulum run accurately. The topics covered include the dimensional stability of different pendulum materials, good and poor suspension spring designs, the design of mechanical joints and clamps, effect of quartz on accuracy, temperature compensation, air drag of different bob shapes and making a sinusoidal electromagnetic drive. One whole chapter is devoted to simple ways of improving the accuracy of ordinary low-cost pendulum clocks, which have a different construction compared to the more expensive designs of substantially well-made ones. This book will prove invaluable to anyone who wants to know how to make a more accurate pendulum or pendulum clock.Less

Accurate Clock Pendulums

Robert J. Matthys

Published in print: 2004-06-03

The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a pendulum clock's accuracy resides in its pendulum. If the pendulum is accurate, the clock will be accurate. This book describes many scientific aspects of pendulum design and operation in simple terms with experimental data, and little mathematics. It has been written, looking at all the different parts and aspects of the pendulum in great detail, chapter by chapter, reflecting the degree of attention necessary for making a pendulum run accurately. The topics covered include the dimensional stability of different pendulum materials, good and poor suspension spring designs, the design of mechanical joints and clamps, effect of quartz on accuracy, temperature compensation, air drag of different bob shapes and making a sinusoidal electromagnetic drive. One whole chapter is devoted to simple ways of improving the accuracy of ordinary low-cost pendulum clocks, which have a different construction compared to the more expensive designs of substantially well-made ones. This book will prove invaluable to anyone who wants to know how to make a more accurate pendulum or pendulum clock.

Over time, several different materials have been used for the pendulum rod such as steel, wood, and invar. The best material is quartz because of its proven stability and low thermal expansion. Steel ...
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Over time, several different materials have been used for the pendulum rod such as steel, wood, and invar. The best material is quartz because of its proven stability and low thermal expansion. Steel is used for the pendulum rod in simple ordinary clocks because it is cheap and has relatively low thermal expansion. Wood is sometimes recommended because of its low linear thermal expansion coefficient along the grain, but it is an inherently unstable material. It warps, splits, and exhibits a high mechanical creep under load. Worst of all, wood expands and contracts considerably with relative humidity. Invar is a mixture of 36% nickel and 63% iron. It is magnetic and rusts in a humid environment. A new material of interest for the pendulum rod is carbon fibre, but it may not work too well as a pendulum rod as the epoxy absorbs moisture, changing the rod's length and weight.Less

Pendulum rod materials

Robert James Matthys

Published in print: 2004-06-03

Over time, several different materials have been used for the pendulum rod such as steel, wood, and invar. The best material is quartz because of its proven stability and low thermal expansion. Steel is used for the pendulum rod in simple ordinary clocks because it is cheap and has relatively low thermal expansion. Wood is sometimes recommended because of its low linear thermal expansion coefficient along the grain, but it is an inherently unstable material. It warps, splits, and exhibits a high mechanical creep under load. Worst of all, wood expands and contracts considerably with relative humidity. Invar is a mixture of 36% nickel and 63% iron. It is magnetic and rusts in a humid environment. A new material of interest for the pendulum rod is carbon fibre, but it may not work too well as a pendulum rod as the epoxy absorbs moisture, changing the rod's length and weight.

The big attraction of quartz as a pendulum material is its good dimensional stability over time. Stability over time is the biggest and most needed characteristic in an accurate pendulum. In contrast ...
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The big attraction of quartz as a pendulum material is its good dimensional stability over time. Stability over time is the biggest and most needed characteristic in an accurate pendulum. In contrast to invar, which was known to be unstable almost from its beginning, quartz has a long history of being a stable material. Dimensional stability is not the same as low thermal expansion. If a pendulum is temperature compensated, as all accurate pendulums are, then it does not matter much what the thermal expansion coefficient is, so long as the compensation has been done accurately. The accuracy of temperature compensation is limited by factors other than the thermal expansion coefficient. Because of their low density, quartz pendulum rods do have one drawback: they have a much higher sensitivity to barometric pressure changes than invar.Less

Some practical properties of quartz

Robert James Matthys

Published in print: 2004-06-03

The big attraction of quartz as a pendulum material is its good dimensional stability over time. Stability over time is the biggest and most needed characteristic in an accurate pendulum. In contrast to invar, which was known to be unstable almost from its beginning, quartz has a long history of being a stable material. Dimensional stability is not the same as low thermal expansion. If a pendulum is temperature compensated, as all accurate pendulums are, then it does not matter much what the thermal expansion coefficient is, so long as the compensation has been done accurately. The accuracy of temperature compensation is limited by factors other than the thermal expansion coefficient. Because of their low density, quartz pendulum rods do have one drawback: they have a much higher sensitivity to barometric pressure changes than invar.

This chapter describes some transient temperature measurements made on a pendulum with a quartz pendulum rod. Time offset error occurs because different parts of the pendulum change temperature at ...
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This chapter describes some transient temperature measurements made on a pendulum with a quartz pendulum rod. Time offset error occurs because different parts of the pendulum change temperature at different rates. Before and after a temperature change, the pendulum is the right length (hopefully) and runs at the right rate. But during the temperature change, the pendulum is the wrong length, due to its different parts changing temperature at different rates, and it runs at the wrong rate during the temperature change interval. Experiments were carried out to measure the pendulum temperatures using small thermistors. The pyrex sleeve provides about one-third of the temperature compensation, while two thin-walled pyrex tubes located on opposite sides of the quartz pendulum rod provide the other two-third. The temperature data provide an interesting look into the thermodynamics of a pendulum. The suspension spring assembly changes temperature relatively slowly, whereas the bob, with its large thermal mass, changes temperature the slowest of any part of the pendulum.Less

Transient temperature effects in a pendulum

Robert James Matthys

Published in print: 2004-06-03

This chapter describes some transient temperature measurements made on a pendulum with a quartz pendulum rod. Time offset error occurs because different parts of the pendulum change temperature at different rates. Before and after a temperature change, the pendulum is the right length (hopefully) and runs at the right rate. But during the temperature change, the pendulum is the wrong length, due to its different parts changing temperature at different rates, and it runs at the wrong rate during the temperature change interval. Experiments were carried out to measure the pendulum temperatures using small thermistors. The pyrex sleeve provides about one-third of the temperature compensation, while two thin-walled pyrex tubes located on opposite sides of the quartz pendulum rod provide the other two-third. The temperature data provide an interesting look into the thermodynamics of a pendulum. The suspension spring assembly changes temperature relatively slowly, whereas the bob, with its large thermal mass, changes temperature the slowest of any part of the pendulum.

This chapter focuses on current knowledge about how shear strength (the force needed to slide one surface over another) originates at the atomic level. For adhesive friction, friction originates from ...
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This chapter focuses on current knowledge about how shear strength (the force needed to slide one surface over another) originates at the atomic level. For adhesive friction, friction originates from the forces needed to move the atoms on one surface over the atomic structure of the opposing surface. The Frenkel-Kontrova model, the Tomlinson model, and molecular dynamic simulations are typically used to show how the atomic structure of the surfaces leads to static friction. One exciting aspect of these friction models is the prediction of superlubricity or negligible friction for incommensurate sliding surfaces, which is now being realized in experiments. As atoms and molecules slide over surfaces, kinetic friction originates from phonon and electronic excitations; the last part of this chapter discusses how these energy dissipation mechanisms are studied with the quartz crystal microbalance (QCM) and the blow-off techniques.Less

ATOMISTIC ORIGINS OF FRICTION

C. Mathew Mate

Published in print: 2007-12-01

This chapter focuses on current knowledge about how shear strength (the force needed to slide one surface over another) originates at the atomic level. For adhesive friction, friction originates from the forces needed to move the atoms on one surface over the atomic structure of the opposing surface. The Frenkel-Kontrova model, the Tomlinson model, and molecular dynamic simulations are typically used to show how the atomic structure of the surfaces leads to static friction. One exciting aspect of these friction models is the prediction of superlubricity or negligible friction for incommensurate sliding surfaces, which is now being realized in experiments. As atoms and molecules slide over surfaces, kinetic friction originates from phonon and electronic excitations; the last part of this chapter discusses how these energy dissipation mechanisms are studied with the quartz crystal microbalance (QCM) and the blow-off techniques.

This chapter discusses the physical principle, design, and characterization of piezoelectric scanners, which is the heart of STM and AFM. The concept of piezoelectricity is introduced at the ...
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This chapter discusses the physical principle, design, and characterization of piezoelectric scanners, which is the heart of STM and AFM. The concept of piezoelectricity is introduced at the elementary level. Two major piezoelectric materials used in STM and AFM, quartz and lead zirconate titanate ceramics (PZT), are described. After a brief discussion of the tripod scanner and the bimorph, much emphasis is on the most important scanner in STM and AFM: the tube scanner. A step-by-step derivation of the deflection formula is presented. The in-situ testing and calibration method based on pure electrical measurements is described. The formulas of the resonance frequencies are also presented. To compensate the non-linear behavior of the tube scanner, an improved design, the S-scanner, is described. Finally, a step-by-step procedure to repole a depoled piezo is presented.Less

Piezoelectric Scanner

C. Julian Chen

Published in print: 2007-09-01

This chapter discusses the physical principle, design, and characterization of piezoelectric scanners, which is the heart of STM and AFM. The concept of piezoelectricity is introduced at the elementary level. Two major piezoelectric materials used in STM and AFM, quartz and lead zirconate titanate ceramics (PZT), are described. After a brief discussion of the tripod scanner and the bimorph, much emphasis is on the most important scanner in STM and AFM: the tube scanner. A step-by-step derivation of the deflection formula is presented. The in-situ testing and calibration method based on pure electrical measurements is described. The formulas of the resonance frequencies are also presented. To compensate the non-linear behavior of the tube scanner, an improved design, the S-scanner, is described. Finally, a step-by-step procedure to repole a depoled piezo is presented.

This chapter describes five different ways of fastening things to a quartz pendulum rod. To connect to a metal rod, a hole is drilled in it or a thread is cut on it. But how do you fasten something ...
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This chapter describes five different ways of fastening things to a quartz pendulum rod. To connect to a metal rod, a hole is drilled in it or a thread is cut on it. But how do you fasten something to quartz? Quartz is like glass it is brittle and breaks easily. Five types of fasteners are described here, with some pros and cons on each. The five fasteners are cemented sleeve, clamp ring, solder joint, dowel pin, and split sleeve. Any of the fasteners can be used at either the top or bottom of a quartz rod, for connecting to a suspension spring, bob, or rating nut. In most cases, the fastener material should be invar because of its low thermal expansion coefficient.Less

Fasteners for quartz pendulum rods

Robert James Matthys

Published in print: 2004-06-03

This chapter describes five different ways of fastening things to a quartz pendulum rod. To connect to a metal rod, a hole is drilled in it or a thread is cut on it. But how do you fasten something to quartz? Quartz is like glass it is brittle and breaks easily. Five types of fasteners are described here, with some pros and cons on each. The five fasteners are cemented sleeve, clamp ring, solder joint, dowel pin, and split sleeve. Any of the fasteners can be used at either the top or bottom of a quartz rod, for connecting to a suspension spring, bob, or rating nut. In most cases, the fastener material should be invar because of its low thermal expansion coefficient.

Chapter 5 examines one of Sha Po’s most fascinating and important periods of cultural development, the Bronze Age, a period during which the local community was making wider and more specialised use ...
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Chapter 5 examines one of Sha Po’s most fascinating and important periods of cultural development, the Bronze Age, a period during which the local community was making wider and more specialised use of the coastal landscape. On the plateau there was some form of stilt-house settlement associated with the specialised manufacture of fine quartz rings, while on the backbeach we have the region’s best evidence for non-ferrous metallurgy in the form of in situ bronze casting. The evidence for craft specialisation tells us that society was undergoing change and could perhaps support the work of artisans through some form of surplus production of food. Moreover, access to more advanced technology and exotic materials are both indications of a widening of external contacts, trade, and exchange, while a heightened interest in personal ornamentation and display points towards greater competition and the emergence of social hierarchies.Less

Bronze Age: Technology, Trade, and Increasing Social Complexity

Mick AthaKennis Yip

Published in print: 2017-02-01

Chapter 5 examines one of Sha Po’s most fascinating and important periods of cultural development, the Bronze Age, a period during which the local community was making wider and more specialised use of the coastal landscape. On the plateau there was some form of stilt-house settlement associated with the specialised manufacture of fine quartz rings, while on the backbeach we have the region’s best evidence for non-ferrous metallurgy in the form of in situ bronze casting. The evidence for craft specialisation tells us that society was undergoing change and could perhaps support the work of artisans through some form of surplus production of food. Moreover, access to more advanced technology and exotic materials are both indications of a widening of external contacts, trade, and exchange, while a heightened interest in personal ornamentation and display points towards greater competition and the emergence of social hierarchies.

This chapter recounts the early attempts at guessing the inner structure of crystals. The Ancients thought quartz was the result of the congelation of water. The first to think that the symmetry of ...
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This chapter recounts the early attempts at guessing the inner structure of crystals. The Ancients thought quartz was the result of the congelation of water. The first to think that the symmetry of quartz was due to a hexagonal packing of elementary particles, in the manner of the honeycomb, was Cardano (1550), but the first serious considerations of the different ways to pack globules were by Kepler in his study of six-cornered snowflakes. These ideas were taken up by Hooke and Bartholin. Huygens explained the double refraction of calcite by a stacking of prolate ellipsoids, Guglielmini related the external shapes of crystals to their shapes at the start of growth, and Bergman showed that the calcite scalenohedron can be interpreted as a stacking of cleavage rhombohedra. Our understanding of crystals was further improved by the observation of the constancy of interfacial angles by Steno in quartz, and observation generalized to all crystals by Carangeot and Romé de l’Isle.Less

Unravelling The Mystery of Crystals: The Forerunners

André Authier

Published in print: 2013-08-01

This chapter recounts the early attempts at guessing the inner structure of crystals. The Ancients thought quartz was the result of the congelation of water. The first to think that the symmetry of quartz was due to a hexagonal packing of elementary particles, in the manner of the honeycomb, was Cardano (1550), but the first serious considerations of the different ways to pack globules were by Kepler in his study of six-cornered snowflakes. These ideas were taken up by Hooke and Bartholin. Huygens explained the double refraction of calcite by a stacking of prolate ellipsoids, Guglielmini related the external shapes of crystals to their shapes at the start of growth, and Bergman showed that the calcite scalenohedron can be interpreted as a stacking of cleavage rhombohedra. Our understanding of crystals was further improved by the observation of the constancy of interfacial angles by Steno in quartz, and observation generalized to all crystals by Carangeot and Romé de l’Isle.

Microstructures in granitic rocks essentially concern quartz grains which deliver key indications on the conditions of deformation of these rocks (magmatic versus high- or low-temperature ...
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Microstructures in granitic rocks essentially concern quartz grains which deliver key indications on the conditions of deformation of these rocks (magmatic versus high- or low-temperature solid-state) based on physical metallurgy concepts (dislocations, slip systems, grain size . . .). Shape preferred orientations of minerals (biotite, K-feldspar . . .), or fabrics, help to define the magmatic lineation and foliation that constitute the structural framework. Modes of fabric acquisition are examined, and field and numerical image analysis techniques used for their study are detailed. Sections include those entitled granite microstructures, fabrics in granites, the fabric of the Brâme–St Sylvestre–St Goussaud complex and the use of digital imagery, including the intercept technique and the analysis of two-dimensional wavelets.Less

Microstructures and fabrics of granites

Anne NédélecJean-Luc Bouchez

Published in print: 2015-01-08

Microstructures in granitic rocks essentially concern quartz grains which deliver key indications on the conditions of deformation of these rocks (magmatic versus high- or low-temperature solid-state) based on physical metallurgy concepts (dislocations, slip systems, grain size . . .). Shape preferred orientations of minerals (biotite, K-feldspar . . .), or fabrics, help to define the magmatic lineation and foliation that constitute the structural framework. Modes of fabric acquisition are examined, and field and numerical image analysis techniques used for their study are detailed. Sections include those entitled granite microstructures, fabrics in granites, the fabric of the Brâme–St Sylvestre–St Goussaud complex and the use of digital imagery, including the intercept technique and the analysis of two-dimensional wavelets.

This chapter examines the manner in which time is conceptualised within the contexts of prehistory and deeper history. By privileging historical records, it shows how the federal recognition process ...
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This chapter examines the manner in which time is conceptualised within the contexts of prehistory and deeper history. By privileging historical records, it shows how the federal recognition process also subordinates oral tradition or archaeological evidence, creating circumstances where dynamic, contingent histories are replaced by strategic essentialism with embedded notions of static and timeless cultures. The chapter looks at quartz crystals placed in the corners of the Magunkaquog building foundation in Ashland, Massachusetts to call attention to parallel processes, a variety of liminality between the ancient past and present (late eighteenth and early nineteenth centuries) — neither past nor present — when ancient beliefs with cultural plasticity were woven into Christian structures. This archaeological example illustrates the presencing of the past and suggests that we cannot understand processes of hybridisation unless we stop dignifying the prehistory-history divide.Less

The Tyranny of Prehistory and the Search for a Deeper History

Stephen A. Mrozowski

Published in print: 2013-11-28

This chapter examines the manner in which time is conceptualised within the contexts of prehistory and deeper history. By privileging historical records, it shows how the federal recognition process also subordinates oral tradition or archaeological evidence, creating circumstances where dynamic, contingent histories are replaced by strategic essentialism with embedded notions of static and timeless cultures. The chapter looks at quartz crystals placed in the corners of the Magunkaquog building foundation in Ashland, Massachusetts to call attention to parallel processes, a variety of liminality between the ancient past and present (late eighteenth and early nineteenth centuries) — neither past nor present — when ancient beliefs with cultural plasticity were woven into Christian structures. This archaeological example illustrates the presencing of the past and suggests that we cannot understand processes of hybridisation unless we stop dignifying the prehistory-history divide.